Several developments have been suggested to reduce the amount of labor in connection with replacing cutter rings on cutters for tunnel drilling machines. This work is time consuming and the T.B.M. as such is out of operation for long periods of time which to a large extent may influence the progress and also the costs.
One solution to this problem has been achieved with a divided cutter ring and especially with a wedge shaped ring clamp securing the divided cutter ring such as described in NO-PA 883 533. Although the replacement operation has been facilitated substantially, loosening of the ring clamp still may be time consuming when replacing the cutter ring segments, as the ring clamp has a tendency to jam due to the large force used when tightening the bolts.